Bart-Pumphrey syndrome ... (Bart-Pumphrey syndrome) - Gen GJB2.

Syndrome Bart-Pumphrey is a disorder characterized by abnormal nails and skin, and hearing loss. In general, skin abnormalities become evident throughout childhood and can include leukonychia, thick and brittle nails, skin growths warty knuckles fingers and toes and palmoplantar keratoderma. In addition, affected individuals show a hearing loss ranging from moderate to profound and often is present from birth. Signs and symptoms of this disease can vary even within the same family. While nearly all affected individuals show hearing loss, they may have different combinations of the other associated features.

This process is due to mutations in the GJB2, located in the long arm of chromosome 13 (13q11-q12). This gene encodes the protein binding Gap beta-2, more commonly known as connexin 26. The connexin 26 channels so as to allow the transport of nutrients, ions and molecules of signaling between cells. Connexin 26 was found in cells throughout the body, including the inner ear and skin. In the inner ear, consisting of connexin 26 channels are in the cochlea. These channels can help maintain the proper level of potassium ions required for converting sound waves into electrical nerve impulses. This conversion is essential for normal hearing. Moreover, connexin 26 may be involved in the maturation of certain cells of the cochlea. Connexin 26 also plays a role in the growth, maturation and stability of the epidermis.

They have identified at least two mutations in people with GJB2 Bart-Pumphrey syndrome. The identified genetic changes replacing the amino acid glycine by serine at amino acid position 59 of the protein (or Gly59Ser G59S) or the amino acid asparagine replaced by the amino acid lysine at position 54 (Asn54Lys or N54K). Altered protein probably disrupts normal function of connexin 26 in cells. This variation could affect the growth of the skin and alter hearing by converting sound waves into nerve impulses.

Syndrome Bart-Pumphrey is inherited as an autosomal dominant, which means that a copy of the altered gene in each cell is sufficient to express the disease. In most cases, an affected person has a parent with the disease. Other cases are due to new mutations in the gene and occur in people with no history of disease in your family.

Tests in IVAMI: in IVAMI perform detection of mutations associated with Bart-Pumphrey syndrome by complete PCR amplification of exons GJB2, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).